Heater manuals we have a proformance plus HW275 pool water heater and I don't have a manual for it just turned it back on and the programming screen has come up with P51 don't know what this means

read http://www.zodiacpoolsystems.com/~/media/Zodiac/Global/Downloads/0748-91071/6919

To answer your question....... ensure all flow is good, cleaning the filter, and correct speed if you have a variable speed pump (typically 2500rpm)

If the flow is good and this is happening then it could be the thermal regulator which is on the header of the heater where the water goes in and out. They can get a build up of scale and or corrosion which causes an internal flow issue and can overheat the heater.

The heater also has high limit sensors which will shut the heater off when it gets too hot.
You will want to make sure to get this fixed to avoid melting of the plumbing or internal damage of the heater.

the minimax 250 m manual is the same for the ch model.

Sounds as If it is electrically heated if so you have a heating element out. The board senses it and shuts it down. It could be a programing problem i have provided the manual for it below is the link.Remember to rate my solution and leave testimonial it is how i earn my accomplishments Thanks

http://www.pentairpool.com/pdfs/MiniMaxNTHeater-DDTC-IG.pdf

Go to the Pentair website and you should find a manual you can download for free.

I don't have a manual but I might help you get it going anyway. The first thing is to connect the tubing from the two ports on the pool to the pump system. There may be valves and if there are then they should be put in line with these tubes. The port that is connected to the skimmer system (it should have something to catch leaves, etc.) should be connected through the tubes and valve directly to the pump. The other port should be connected to the other available port on the pump system. The pump can then be connected to power. Before turning on the pump you first need to prime the pump. this can be done by running a water hose down the skimmer system with the water on. It should fill t he pump, filter and any other part of the system with water and return air and some water back to the pool. Once you can tell that water and virtually all the air is has returned to the pool then you can remove the hose and turn on the pump. Once water is circulating through the pump you need to get the chemicals right in the pool. Basically you need to shock the pool to 10 ppm with vinyl safe shock, add stabilizer to 30 ppm and if your system is a salt system it should have about 3000 ppm of salt. If you don't have a salt system then you will need to have a floating chlorinator filled with chlorine tablets. I suggest buying test strips to test these concentrations. It is safe to swim when the chlorine is between 2 and 4 ppm and you can clearly see the bottom and there is no dirt at the bottom. If you don't have a vacuum hose, head and pole then I recommend you buy one. I hope this helps and you may get better results with the request for a manual if you made the same request on the FixYa's "Pool Pump" category or contact Intex technical support line. I hope this helps but feel free to contact me with further questions.

pentairpool.com

Here is a link to the Aqualink website so you can download a trouble shooting guide.